1. Field of the Invention
The present invention relates to a suction pad for attracting an annular workpiece having an opening at its central portion, for example, a compact disk-recordable (CD-R).
2. Description of the Related Art
In general, a vacuum-attracting apparatus, which is based on the use of a suction pad, is adopted as a transport means for an annular workpiece (hereinafter simply referred to as xe2x80x9cworkpiecexe2x80x9d) having an opening at its central portion. It is known that the suction pad, which is used for the vacuum-attracting apparatus, is constructed, for example, as disclosed in Japanese Laid-Open Utility Model Publication No. 62-172582.
The suction pad includes an inner seal member, an outer seal member for surrounding the inner seal member, and a pad-supporting member to be fitted to the outer seal member. A vacuum-attracting groove, which is formed between the inner seal member and the outer seal member, communicates with a vacuum-attracting hole which is formed in the pad-supporting member. An aspirator is operated to attract the workpiece by the aid of the vacuum-attracting groove and the vacuum-attracting hole. Accordingly, the workpiece is attracted to the inner seal member and the outer seal member.
However, the suction pad concerning the conventional technique described above involves the following drawback. That is, for example, when the workpiece has any strain or warpage, it is impossible to attract and hold the workpiece horizontally. Therefore, the workpiece is transported in a state of being inclined. An inconvenience arises such that a large number of workpieces cannot be stacked at a correct position or in a correct attitude on a workpiece-stacking apparatus.
When the workpiece is repeatedly transported many times, then the inner seal member and the outer seal member, which serve as the attracting section for the workpiece, are abraded, and it is necessary to exchange the suction pad with new one. However, in the case of the suction pad described above, the outer seal member and the pad-supporting member are tightly fitted and integrated into one unit. Therefore, an inconvenience arises such that the exchange operation for the outer seal member is complicated.
A general object of the present invention is to provide a suction pad which makes it possible to attract and hold a workpiece horizontally and stack the workpiece at a correct position and in a correct attitude on a workpiece-stacking apparatus, even when the workpiece has any strain or warpage.
A principal object of the present invention is to provide a suction pad which makes it possible to easily exchange a workpiece-attracting section separately from a holding section.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.